The present invention relates to an angular drive for a dental prophylactic device or cup which may contain prophylactic material for massage into the tooth, and which is adapted to polish or otherwise treat the surface of a tooth.
Essentially, the present structure is a handheld tool which may be operated in any suitable manner as from the main drive of the dental handpiece, either belt, air or electrically driven, or in any other manner and which will provide an appropriate handle structure so that the device may readily be grasped by the user. In addition, it is necessary that the handle be structured in such a manner so as to facilitate the application of the prophylactic material to the operating surface of the tooth, i.e., at an angle approximately 90.degree. to the handle itself.
In the present invention, the handle carries the internal drive means for the particular operating device and the interconnecting elements between the operating elements and the application device. Heretofor, in applying a paste by rotary means to a tooth, the rotational speeds are limited in traditional prophylactic angled devices because centrifugal forces cause the prophylactic paste to fly off the rotating prophylactic cup when speeds are increased beyond approximately 2,000 to 2,500 rpm. This condition requires either the utilization of relatively low speeds or of viscous pastes which are not necessarily optimum for prophylaxis.
An important feature and object of the present invention is the replacement of the rotating, polishing and prophylactic carrying cup with a cup which oscillates through an arc of at least 50.degree. to approximately 150.degree.. In the operation of the device, according to the present invention, the stopping and reverse rotation will stop the paste from moving off the cup. As a result, oscillation cycles may be increased to as much as 12,000 rpm without the presently known problem of the paste flying off the cup. This increased oscillation cycling speed should result in improved tooth cleaning efficiencies and also make possible the utilization of various new types of prophylactic pastes.
Also, in the operation of prophylactic devices of the type herein referred to, a constant rotation in a single direction causes the device to move off the particular location on the tooth in a direction dictated by rotational forces so that full control is maintaned only with application of a constant counterforce on the handle.
An object of the present invention, therefore, is, by use of a reciprocating device, to obviate the result which occurs from constant rotation in a single direction and makes the instrument drift from a spot on which it is being used and is intended to be used.
One of the major problems in the operation of prophylactic devices using rotational movement is generated by the use of the toothed drive gears in the angular drive from the structure in the handle to the operating structure. These right angle gears, when operated at speeds of 1,500 to 2,500 rpm, tend to act like a pump pulling the debris, saliva and foreign matter into the angle head and so causing malfunction and premature wear. This necessitated the need to add seals to the construction of traditional angular driving devices to reduce this objectionable condition.
A further object of the present invention, therefore, is the utilization of a reciprocating cam follower translated into an oscillating motion at the cup to obtain smoother running and a longer life, thus obviating the need for gears and their inherent problems also enabling the provision of a seal which will be able to retain lubricants inside the angularly disposed head.
In addition to the advantages which accrue from the oscillating motion of the cleaning cup, a longer arc of oscillation is made possible, that is an arc of oscillation of the order of 120.degree., providing for more positive action. This is obtained through the utilization of an oscillating longitudinal cam follower which oscillates axially of the drive shaft and is translated into the oscillating motion of the prophylactic cup by a slot in the surface of the oscillating cam carrying the cup which is parllel to its axis and is engaged by the longitudinal member. The longitudinal member, as it is translated around the axis of the drive, is oscillated by its contact with the stationary cam follower track which is concave surfaced and which causes the longitudinal member to oscillate when it is translated around the axial center of the drive.
Another and important object of the present invention, therefore, is the provision of a longitudinal oscillating cam follower interconnected with a slot parallel to the axis of the angled applying cup wherein the longitudinal oscillation of the cam follower is simply obtained by having the cam follower arranged parallel to the axis of the drive member and translating the same around the axis of the drive member while the cam follower, optionally, is spring biased against a stationary cam follower track in the drive member which causes the cam follower to oscillate.
It should be borne in mind that this kind of drive may well be utilized in other dental operating devices such as endodontic reamers, broaches and other canal opening devices.
The present invention, therefore, also has as an object the provision of a structure which permits the utilization and impingement of greater loads or torque on the prophylactic cup during prophylaxis because of the positive action of the mechanism, thereby further improving cleaning and other operating efficiencies.